Voltage regulator



Sept. 9, 1947. w. J. PocH VOLTAGE REGULATOR F11eDeo. 20, 1943 nnnv:

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n Tram/fr Famed sept. 9', 1947` VOLTAGE REGULATOR Waldemar J. Poeh, Moorestown, N. J., assigner to Radio Corporation of America, a corporation of Delaware Application December 20, 1943, Serial No. 515,038

Claims.

This invention pertains vgenerally to regulated power supply circuits and more particularly to a voltage regulator for a source of rectied and filtered alternating potential wherein the regulator provides a power source having substantially constant output voltage and eiectively low output impedance.

Various types of voltage regulators have been used heretofore in conjunction with conventional power supply circuits for thermionic tube apparatus. Besides regulating the output voltage of a power supply within predetermined small limits, one of the prime requisites of a voltage regulator is to provide a power source having extremely low eiiectivey output impedance in order that variations in load or source impedances may have minimum effect upon the regulated output voltage.

The instant invention is related to the invention described in a copending U. S. application, Serial No. 491,420, filed June 18, 1943, by Ralph V. Little, Jr., and assigned to the same assignee as this application. Both inventions contemplate the use of a thermionic regulator tube having an anode, a cathode and at least one control electrode wherein the anode-cathode circuit of the tube provides a shunt impedance path across the output of a filter which is connected to the output of a conventional high voltage rectifier or other unregulated direct voltage source. A voltage divider, comprising a pair of seriallyconnected resistors, also is connected across the output of the filtered power supply. In the -instant invention the anode of a thermionic tube amplifier is connected, through lan anode resistor, to the positive output terminal of the filtered power supply. The cathode of the ampliiler tube is connected, through an adjustable slider contact, to a selected point on the voltage divider, whereby the output voltage provides cathode drive, in the proper phase, of the anipliiler input circuit. The anode of the amplifier tube is connected, for example, through a one microfarad capacitor to the control electrode of the thermionic regulator tube.

Brieily, the operation of the system is as follows: The regulator tube provides a shunt impedance path across the output of the filtered power supply. A portion of the regulated output voltage controls the amplier tube which is cathode coupled to the voltage divider. Suitable phase reversal is provided thereby for applying regulating alternating voltages through the capacitor to the control electrode of the thermlonic regulator tube, thereby degeneratively varying the impedance of the regulator tube and hence the shunt impedance path across the ltered power supply.

It will be seen that the circuit will compensate readily for substantially all except very low frequency line surges, for residual hum and for fluctuations caused by all except very low frequency variations in source and load impedances. Since the output voltage will remain substantially constant, notwithstanding such variations in applied voltage and in load impedances, the effective output impedance of the circuit will be extremely low at all except extremely low frequencies. The use of large capacitors across the output of the regulated voltage source therefore becomes unnecessary, resulting in considerable economy in space and cost. The capacitive coupling between the amplifier anode and the regulator grid permits both tubes to be operated at normal and eflicient voltages from the conventional rectiied voltage source, thereby eliminating the disadvantages of direct coupled amplifiers.

Among the objects of the invention are to provide an improved voltage regulator for a. source of uni-directional Voltage. A further object is to provide an improved voltage regulator having a relatively small static current drain. Another object of the invention is to provide an improved voltage regulator for a uni-directional voltage source wherein va portion of the output regulated voltage is applied to an amplifier which is capacitively coupled to a regulator tube to vary degeneratively the shunt impedance of said regulator tube which is connected across the unidirectional voltage source.

A further object of the invention is to provide an improved regulator circuit for controlling the output voltage of 'a filtered power supply circuit wherein a portion of the regulated output voltage is applied through cathode-coupling to an amplier tube to provide degenerative control potentials which are capacitively coupled to the control electrode of a thermionic regulator tube connected across the output of the filtered power supply. Another object of the invention is to provide an improved voltage regulator for a source of uni-directional potential wherein maximum voltage regulation and an effectively low power supply output impedance are provided. A further object of the invention is to provide an improved voltage regulator for a source of uni-directional potential wherein substantially constant output voltage and effectively low power supply output impedance are accomplished Without the necessity of employing relatively large capacitors across the output of the voltage regulator.

The invention will be described in further detail by reference to the accompanying drawing of which the single figure thereof is a schematic circuit diagram of a preferred embodment.

Referring to the drawing, the circuit includes a conventional filtered high voltage power supply which comprises a power transformer I having a primary winding l2` connected to a source of alternating potential, not shown. The terminals of the high voltage secondary Winding 3 are connected to the anodes of a full wave rectifier tube 4. A cathode of the full wave rectifier tube 4 is connected to a low voltage secondary winding 5 of the transformer I. The cathode of the rectifier tube 4 is also connected to the positive output terminal 6. The center tap of the high voltage secondary winding of the transformer I is connected, through a relatively high reactance coil 1, to the grounded negative output terminal 6'. A first filter capacitor 8 is connected between the cathode of the rectifier tube 4 and the center tap of the high voltage secondary winding 3 of the transformer I. A second filter condenser 9 is connected from the cathode of the rectifier tube 4 to the grounded output terminal of the reactance coil 1.

The anode of a thermionic regulator tube I0, which, for example, may be a type 6Y6G tube, is connected to the cathode of the rectifier tube 4. The anode is also connected, through a screen coupling resistor I I, to the screen electrode of the regulator tube I0. The cathode of the regulator tube I is connected to the grounded terminal of the filtered power supply circuit. Suitable negative bias potential for the control electrode of the thermlonic regulator tube III is applied thereto through series resistors I2, I3, one of which is connected to the center tap of the high voltage secondary winding 3 of the transformer I. Additional filtering of this bias potential is provided by a third lter capacitor I4 connected between the junction of the series resistors I2, I3, and the grounded terminal of the power supply circuit.

The anode of an amplifier tube I is connected, through an anode coupling resistor I8, to the positive output lterminal 6. and to the cathode of the rectifier tube 4. A voltage divider, comprising a pair of serially connected resisitors I6, I1, is connected between thev output terminals 8 and B'. An adjustable contact I8 operable upon the series resistor I6, is connected to the cathode of the amplifier tube I5. The control electrode of the amplifier tube I5 is connected to the screen electrode of the regulator tube I0, and is coupled to the grounded output terminal 6' through a capacitor I9.

Variations in the output voltage at the output terminals 6, 6' will be applied degeneratively to drive the cathode of th'e amplifier tube I5. /The anode of the amplifier tube I5 is coupled, through a coupling capacitor 20, to the control electrode of the thermlonic regulator tube II).

It should be understood that various modifin cations of the amplifier circuit disclosed herein may be employed for degeneratively utilizing a portion of the regulated output voltage to control the impedance of the thermionic regulator tube which is connected across the output of the filtered power supply,

Thus the invention disclosed comprises an improved voltage regulator circuit for a souri?? 0i uni-directional potential wherein n, portion o! the regulated output voltage is coupled degeneratively to a control electrode of a thermlonic regulator tube comprising a shunt impedance path across the output of the source of unl-di rectional potential.

It should be understood that the disclosed circuit does not regulate the D.C. output itself. If the line Voltage increases, the output voltage increases also, but it does so quite slowly so that any sudden surges, normally quite troublesome, are almost entirely eliminated. In other words, very low frequency disturbances are attenuated but D.C. changes in output voltage may still take place.

I claim as my invention:

1. A voltage regulator for a source of direct voltage including a thermlonic regulator tube having a cathode, an anode and at least one control electrode, means including said tube providing a shunt impedance path across said voltage source, a thermionic amplifier tube connected across said source, means for applying said voltage to said amplifier tube to derive a control potential, and series capacitive coupling means for applying said control potential to said regulator tube to vary degeneratively said shunt impedance in response to variations in said direct voltage.

2. A voltage regulator for a source of direct voltage including a thermlonic regulator tube having a cathode, an anode and at least one control electrode, means including said tube providing a shunt impedance path across said voltage source, a thermlonic amplifier tube connected y across said source, means for applying said voltage to said amplifier tube to derive a control potential, and capacitive means for applying said control potential degeneratively to said control electrode of said regulator tube to vary said shunt impedance in response to variations in said direct voltage.

3. A voltage regulator for a source of direct voltage including a thermlonic regulator tube having a cathode, an anode and at least one control electrode, means including said tube providing a shunt impedance path across said voltage source, a thermionic amplifier tube, means for applying said voltage to said amplifier tube, and a capacitor coupling said amplifier tube to said regulator tube for 'varying said shunt impedance in response to variations in said direct voltage.

4. A voltage regulator for a source of direct voltage including a thermlonic regulator tube having a cathode, an anode and at least one control electrode, means including said tube providing a shunt impedance path across said voltage source, a thermionic amplifier tube, means for applying said voltage to said amplifier tube, and capacitive means coupling said amplifier tube to said control electrode of said regulator tube for varying degeneratively said shunt impedance in response to variations in said direct voltage.

5. A voltage ,regulator for a source of direct voltage including s a thermlonic regulator tube having a cathode, an anode and at least one control electrode, means including said tube providlng a shunt impedance path across said voltage source, a thermlonic amplifier tube having at least anode` cathode and control electrodes, means for applying said voltage to said cathode of said amplifier tube, and capacitive means coupling said amplifier tube to said control electrode of said regulator tube for varying degeneratively seid shunt impedance in response to variations in 1t UNITED STATES PATENTS said direct vo ase- Number Name Date WAI-DEMAR J- POCH- 2,299,942 Trevor Oct. 27, 1942 REFERENCES CITED 5 FOREIGN PATENTS The following references are of record in the Number Country Date y le of this patent: 472,326 Great Britain Sept. 22, 1937 

